linux-kernel - Re: [PATCH 9/9] power: supply: twl4030-charger: fix OF sibling-node lookup

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Date:   Wed, 22 Aug 2018 23:36:58 +0200
From:   Sebastian Reichel <sre@...nel.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Frank Rowand <frowand.list@...il.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable <stable@...r.kernel.org>, NeilBrown <neilb@...e.de>,
        Felipe Balbi <balbi@...com>
Subject: Re: [PATCH 9/9] power: supply: twl4030-charger: fix OF sibling-node
 lookup

Hi,

On Wed, Aug 22, 2018 at 12:55:47PM +0200, Johan Hovold wrote:
> Use the new of_get_compatible_child() helper to lookup the usb sibling
> node instead of using of_find_compatible_node(), which searches the
> entire tree and thus can return an unrelated (non-sibling) node.
> 
> This also addresses a potential use-after-free (e.g. after probe
> deferral) as the tree-wide helper drops a reference to its first
> argument (i.e. the parent device node).
> 
> While at it, also fix the related phy-node reference leak.
> 
> Fixes: f5e4edb8c888 ("power: twl4030_charger: find associated phy by more reliable means.")
> Cc: stable <stable@...r.kernel.org>     # 4.2
> Cc: NeilBrown <neilb@...e.de>
> Cc: Felipe Balbi <balbi@...com>
> Cc: Sebastian Reichel <sre@...nel.org>
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---

Reviewed-by: Sebastian Reichel <sre@...nel.org>

-- Sebastian

>  drivers/power/supply/twl4030_charger.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/supply/twl4030_charger.c b/drivers/power/supply/twl4030_charger.c
> index bbcaee56db9d..b6a7d9f74cf3 100644
> --- a/drivers/power/supply/twl4030_charger.c
> +++ b/drivers/power/supply/twl4030_charger.c
> @@ -996,12 +996,13 @@ static int twl4030_bci_probe(struct platform_device *pdev)
>  	if (bci->dev->of_node) {
>  		struct device_node *phynode;
>  
> -		phynode = of_find_compatible_node(bci->dev->of_node->parent,
> -						  NULL, "ti,twl4030-usb");
> +		phynode = of_get_compatible_child(bci->dev->of_node->parent,
> +						  "ti,twl4030-usb");
>  		if (phynode) {
>  			bci->usb_nb.notifier_call = twl4030_bci_usb_ncb;
>  			bci->transceiver = devm_usb_get_phy_by_node(
>  				bci->dev, phynode, &bci->usb_nb);
> +			of_node_put(phynode);
>  			if (IS_ERR(bci->transceiver)) {
>  				ret = PTR_ERR(bci->transceiver);
>  				if (ret == -EPROBE_DEFER)
> -- 
> 2.18.0
> 

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